The following is based on a true story. The names of some characters have been changed to protect their identity.

Lydia Johnson lay on a beach, far from everything. The only things she could sense were the steady breathing of her fiance, the sunlight set to "tan" instead of "sweat", and the soft white sand beneath her.

She never wanted to go back to work. She'd take this holiday instead of her overcrowded beehive of an office in Hong Kong any day. But she decided not to think about anything unpleasant until she had to. And suddenly, she had to.

Her eyes snapped open. "Did you hear that?" she exclaimed, pulling her fiance from the depths of tranquility.

"You won't believe what I just heard. I heard my old professor talking!"

"If you insist," he sighed tiredly and flopped back, hoping the incident wasn't an indicator of their future married life.

Lydia shut her eyes. But the voice returned: "Please don't be afraid. I know it must be a shock to hear me, but it's the easiest way I could think of. I used to work at Canossa Hospital, Old Peak Road, and we'd like to help you."

She sat up again - quietly - so she did not disturb Rob and stared across the vast shoreline and bluish-green ocean. Rob was right, they were alone.

She began to worry.

"Rob ..."

She shook him. "Robert!"

He made a mumbling sound as she stood up. "I'm going home."

A week later, she sat in the office of Dr Mabel Mui. She stared at the desk calendar. It had a photograph of a calm, warm beach - much like the one where she had heard the voice. She felt uncomfortable.

The all-white, overly air-conditioned office resembled an Arctic glacier. Gazing at the calendar was the only thing that brought warmth to her body. As Dr Mui entered, Lydia tore her eyes away from the desk.

"So," the young psychotherapist said smilingly, "you're our Joan of Arc, right?" Her enthusiasm was in stark contrast to the unwelcome room.

"It's only one voice - my old professor at medical school telling me about a hospital where he used to work, that he'd like to help me."

"Medical school! Then you must be a doctor?"

"No, I dropped out and became a regional sales director at a large company." Her tone of voice indicated she didn't want to talk about it.

Conversation between them dwindled awkwardly, and she left soon after, with a diagnosis of hallucination, a drug prescription - and an uneasy feeling that it wouldn't help at all.

The voice returned just as Lydia was leaving to go to work one day. She didn't flinch; she reached into her bag, took out the medication and threw it in the gutter. She then headed for Dr Mui's office.

When she arrived, she told her the whole story in the same terse tone as before. Dr Mui was confused:

"He said you needed immediate medical care? But he's the cause of your problem, so why not just leave you alone?"

"Maybe he means you need medical care for something else. It could be your subconscious using your professor's voice to warn you of a hidden illness. Do you have a clean medical record?"

"I've never had anything serious - colds, fevers, my tonsils out when I was 12. No diseases."

"Well, that could be it! Perhaps your subconscious is urging you to get a check-up because it will reveal an illness you're not aware of. Best listen to your prof's voice, maybe because it's trying to help."

Just as Lydia stepped out of the office, the voice came back: "Smart girl that one. She's right, you know."

Lydia stood quietly without responding. The voice continued:

"I suggest Adventist Hospital, 40 Stubbs Road."

She hailed a taxi and told the driver to head for Stubbs Road.

On the way, Lydia called Rob and told him everything. He wasn't convinced, but decided to humour her.

"I'll meet you there; don't go in without me," he said.

She didn't. But when he arrived, so did the voice.

"He's finally here, is he? He sure took his time. In any case, get a brain scan. You've got a brain tumour."

She told Rob.

"No!" he said. "Do you have any idea what brain scans cost? You don't even have symptoms - no headaches, no fits, nothing. Go tell that psychiatrist of yours about this to see if she still thinks it's a good idea."

So she did.

Dr Mui reassured Lydia and told her she'd arrange a brain scan immediately. And she convinced Rob. All three were ready to start with the rescue effort immediately.

But the hospital wasn't.

"What do you mean you won't do it? She's sick!"

With Dr Mui alongside, Rob could be heard arguing loudly with the department head in the hospital. Lydia sat in a corner, waiting to hear if the voice would return.

The head, a tall, bald man called Dr Lancaster Wang, sighed.

"She has no symptoms of a tumour," he said. "Seizures and migraines are very common and she hasn't a trace of either. I'm sorry, but the hospital can't afford to perform a brain scan on somebody who doesn't need it."

Suddenly, he paled.

"I - did you hear that? I heard a man talking to me!" He whirled round to look down the hallway.

It was as empty as Lydia and Rob's holiday beach.

"What's going on here?" Wang asked.

Dr Mui turned to look at Lydia. They both knew what was going on - and so did Rob.

He rubbed his head and took a deep breath, then pivoted on his heel and walked towards a door gesturing to them to follow.

Nobody except Dr Wang was surprised when they discovered a tumour the size of an egg. He gaped at the scan results. Dr Mui flicked him on the head.

"Well?"

"It's - it's a ..." he stuttered, "a meningioma."

"What's that?"

No response. She flicked him again.

He sobered up: "It's a cranial growth that requires immediate surgery before it starts to spread."

"What?"

He looked at Lydia: "It's squashing your brain and will grow if we don't remove it."

"So be it," said Rob. "When can she have the operation?"

"Wait," said Lydia, "what did you hear just now in the hallway?"

Wang shifted uneasily. He answered sheepishly:

"An old man with a British accent told me not to be afraid and that I should get the scan room ready for you."

"So it was my professor," she whispered. The room fell quiet for a moment. She turned and addressed the whole group. "Surgery it is."

Lydia awoke in bed, all alone. The anaesthesia was just starting to drizzle from her bloodstream. She took a moment to remember where she was and smiled at the thought she had been saved.

She wondered if she'd ever hear from her old professor again. What if the voice never came back? It was crazy, but she knew she'd miss him. Come back, she thought, come back. And then, suddenly: "I'm glad I could help you. Goodbye."

She anxiously called out, "You can't leave, you can't, you saved my life!"

But it was no good. The voice was gone.

Mabel and Rob came in, and Mabel immediately noticed the sad and despairing look on her patient's face: "Ah ... you're missing the voice, aren't you?"

Lydia smiled and said: "You really are a pretty good psychiatrist."

"Why don't you just track down your professor?"

"It's not that simple. He's angry with me because I quit medical school."

"Why did you quit - lack of interest?"

"No, I loved it. I was meant to be a doctor, but wasn't good at it. That was the problem - and my parents becoming anxious about the money that they were spending on my tuition. But my professor wanted me to stay and was furious when I left. Anyway, it's too late now for regrets."

Dr Mui looked thoughtful and then said: "So you liked hearing his voice because it made you feel he wasn't angry anymore. It gave you a second chance. You really looked up to him?"

"You're good at this. I feel like you've crawled inside my mind."

"There's been a lot crawling around in your mind lately, hasn't there?" Rob said. "A tumour, a voice and now even Mabel."

"Speaking of which," Dr Mui said, "have you ever wondered what made you hear the voice in the first place?"

Rob intervened: "Might it have been the tumour affecting her brain cells that caused it?"

Dr Wang entered. He'd overheard Rob's question.

"Yes," he said. "Cranial lesions can give rise to these symptoms."

"That's impossible," Lydia replied quickly. "It told me exactly where to go and what to do."

"Well, there have been cases ..."

However, before he could finish, Rob butted in: "I think it's a sign - a sign that you've been forgiven and have another chance."

"At what?" Lydia asked, with a puzzled frown.

"At being a doctor."

Five years later, Dr Lydia Johnson lay on a beach, celebrating her first year as a doctor - trained by her old and recently retired professor.

It was also her fourth marriage anniversary. With her on the beach were her husband, Rob, and also her two close friends, Mabel and Lancaster.

To this day, nobody has been able to establish the cause of the voice. It's a case of believe what you will.

Yet as Lydia often says when quizzed about it: "All's well that ends well ..."